What a Home Energy Auditor Checks During an Assessment

Why a Structured Assessment Matters

Most homeowners have a general sense that their house is draughty or their heating bills are high, but pinpointing the cause requires measurement, not guesswork. Natural Resources Canada's EnerGuide program requires that pre- and post-retrofit audits be performed by a licensed energy advisor registered with a service organization accredited under the program. That credential ensures the assessor uses consistent methods and calibrated equipment, producing results that can be compared across homes and submitted to federal grant programs.

The assessment follows a standardized protocol developed by Natural Resources Canada and documented in HOT2000, the energy modelling software used to calculate EnerGuide scores. Every step is designed to produce data — not impressions — that can be entered into the model and translated into a projected energy use figure in gigajoules per year.

Stage 1: Pre-Visit Data Collection

Before arriving, the assessor typically asks for utility bills covering the past 12 months and basic information about the home: construction year, floor area, fuel types, and the number of occupants. This data seeds the initial HOT2000 model and gives the assessor a benchmark against which actual measurements can be compared.

In older homes — particularly those built before the National Building Code of 1975, which introduced the first meaningful insulation requirements — the assessor may already expect significant air leakage and below-standard insulation depths. In newer builds from the 2000s onward, the gaps more often appear in mechanical systems or thermal bridging at structural connections.

Stage 2: The Exterior Walkthrough

The assessor begins outside, noting the orientation of the building, window-to-wall ratio, roof geometry, and visible condition of the building envelope. They check for:

• Gaps at the foundation-sill interface, which is one of the most common air leakage sites in Canadian construction
• Condition of caulking and flashing around windows, doors, and penetrations
• Evidence of moisture damage or frost staining on exterior cladding, which can indicate vapour barrier failures
• Roof overhangs and their relationship to attic ventilation — inadequate ventilation causes ice damming in cold climates
• Attached garages, which require specific air sealing at the shared wall to prevent exhaust fume infiltration

Stage 3: Interior Inspection by Zone

Inside, the assessor works through the house zone by zone. Each zone has a defined boundary in the HOT2000 model, and conditions within each zone affect the calculated energy load.

Attic and Ceiling Plane

The assessor enters the attic with a measuring tape and a probe to record insulation depth and type at multiple points. In Canadian homes, blown cellulose and mineral wool batt are common in older stock; spray polyurethane foam became widespread in new construction after 2005. The assessor checks for uniform coverage, looking for voids around light fixtures, exhaust fan penetrations, and the hatch itself — all frequent leakage paths.

They also record the attic ventilation arrangement: the ratio of net free area to attic floor area should meet a minimum of 1:300 under most Canadian building codes, rising to 1:150 in some moisture-prone regions.

Walls

Wall assembly details are often inferred from construction era documentation or physical probing at electrical outlets. The assessor removes outlet covers on exterior walls to observe whether batt insulation is present behind the vapour barrier and to look for gaps around the electrical box. In 2×4 framed walls, the maximum achievable nominal R-value is roughly R-13 with fibreglass batt — well below the R-20 or higher now recommended in Climate Zone 6 and 7 cities such as Edmonton, Whitehorse, and Winnipeg.

Basement and Crawlspace

Below-grade spaces present two distinct challenges: the thermal boundary location (is the basement conditioned or unconditioned?) and the moisture regime. The assessor checks whether rim joists — the framing members at the top of the foundation wall — are insulated, since they represent a significant thermal bridge in wood-frame construction. They also note whether the basement floor is insulated and whether a vapour barrier covers any exposed soil in a crawlspace.

Stage 4: The Blower Door Test

The blower door test is the diagnostic centrepiece of the assessment. A calibrated fan is sealed into an exterior doorframe with a flexible panel. The fan depressurizes the house to a standardized pressure difference of 50 Pascals (Pa) relative to outdoors — roughly equivalent to a 32 km/h wind hitting all surfaces simultaneously.

At 50 Pa, the fan flow rate is measured in cubic metres per hour or litres per second. This number, expressed as ACH50 (air changes per hour at 50 Pa), tells the assessor how many times per hour the entire volume of air in the house escapes through gaps at that pressure. A well-sealed modern Canadian house typically measures between 1.0 and 2.5 ACH50. Older homes from the 1960s and 1970s routinely test at 8 to 15 ACH50.

While the fan runs, the assessor or a second technician moves through the house with a smoke pencil or an infrared camera to locate specific leakage sites. Common findings include:

• Bypasses around interior partition walls where they meet the attic floor
• Leakage at the top plates of exterior walls
• Air movement through recessed light fixtures installed before airtight-rated fixtures became standard practice
• Gaps around plumbing stacks and electrical panels where they pass through the ceiling or floor

Stage 5: Mechanical System Review

Heating and cooling equipment accounts for the largest share of energy consumption in most Canadian homes, so the assessor spends considerable time in the mechanical room. They record the fuel type, model number, and estimated efficiency of the furnace or boiler, the age and type of the hot water heater, and whether any mechanical ventilation is present. Key data points include:

• AFUE (Annual Fuel Utilization Efficiency) rating of the furnace — older atmospheric units from the 1980s often operate at 60–70% AFUE compared to 96–98% for condensing models
• Whether a heat recovery ventilator (HRV) or energy recovery ventilator (ERV) is installed and how often filters are changed
• Duct leakage — in forced-air systems, leaky ducts in unconditioned spaces such as crawlspaces or attached garages can waste 20–30% of conditioned air before it reaches living spaces
• Water heater tank size and first-hour recovery rating, or the specifications of a tankless unit

Stage 6: HOT2000 Modelling and the EnerGuide Report

After the site visit, the assessor enters all collected data into HOT2000 and runs the energy model. The software calculates annual energy consumption in gigajoules, factoring in climate data for the nearest weather station, occupant assumptions defined by Natural Resources Canada, and the physical characteristics recorded on-site.

The output is an EnerGuide label showing the home's current score. Scores run from 0 (extremely inefficient) to 100 (net-zero energy ready), with the Canadian average sitting around 61 for existing housing stock. The report also includes a list of recommended upgrades ranked by cost-effectiveness, alongside projected new EnerGuide scores if each measure is implemented.

This post-audit report is what homeowners submit when applying for the Canada Greener Homes Grant or provincial equivalent programs. The report must be completed by a registered energy advisor — not the contractor performing the upgrades — to ensure objectivity.

What the Audit Does Not Cover

A residential energy audit is distinct from a home inspection. The energy assessor is not evaluating structural integrity, electrical safety, or plumbing compliance. They are not looking for mould, radon, or asbestos, though they may note conditions that suggest further testing would be prudent. Homeowners who want a comprehensive picture of their property's condition typically commission both an energy audit and a home inspection separately.

Finding a Registered Energy Advisor in Canada

Natural Resources Canada maintains a directory of registered energy advisors searchable by postal code at the NRCan website. Provincial programs in Ontario, British Columbia, Quebec, and Nova Scotia also maintain their own accreditation networks. Audit costs typically range from $400 to $600 for a pre-retrofit assessment, though several provincial programs partially or fully subsidize the cost for eligible homeowners.